Electrically conducting zeotype frameworks offer a new approach to energy storage technologies. In particular they offer new opportunities in electrical charge storage applications, such as in ultracapacitors, battery electrodes, and ion conducting membranes. Tailored materials with mono-dispersed pore size distribution and large pore density per unit volume have the potential to provide optimal electrical energy storage, in terms of both energy density and power density.
High-surface-area activated carbonaceous materials are most often used for electrical energy storage, but these materials possess random pore sizes and broad distributions leading to sub-optimal charge packing. Nano-carbon material promises better pore size and distribution over mesoporous carbon, but has proved difficult to produce in bulk. While nanostructured materials such as zeolites show more efficient packing than the above materials, they have previously been produced only in electrically insulating forms.
The development of different options for improving electrical energy storage capabilities is essential to meet the current and future requirements for efficient use of electrical energy in applications. New materials are needed to improve charge storage capabilities by increasing both the energy and the power densities, as well as achieving faster recharge times. Electrically conducting framework materials are crucial to the development of new charge storage materials. Porous electrically conducting frameworks allow for high storage densities and for new strategies in which materials simultaneously exploit multiple charge storage and mobility mechanisms. Particularly desirable are microporous zeotype electrically conducting frameworks where pore sizes range from sub-nanometer to 2 nm, and are roughly the size of hydrated and/or solvated ions and small molecules.
Ultracapacitors are of particular interest in the field of electrical energy storage devices. The capacitance of the electrical double-layer (EDLC) forms the basis for ultracapacitors, where the layer is formed between mobile ions in an electrolyte and an electrically conducting plate. The capacitance per unit area is high, due to the short charge separation distance characteristic of ionic double-layers typically atomic in scale. The high attainable capacitance forms the basis for widespread similar electrolytic capacitors. An ultracapacitor adds to this a large effective area of the capacitor plate by employing a porous conducting medium as electrode. The capacitance values correlate with pore dimension and ion size, with pore size distribution, and pore density per unit volume. Thus an electrically conducting microporous zeotype material would function as an ultracapacitor material. A conducting zeotype material may also have additional uses as a novel semiconductor material for electronics and optics applications, in addition to properties and applications already known for zeolities and zeotypes such as catalysis, sorption, separation, ion-exchange membranes, etc.
Therefore, there is a need in the art for the development of conducting microporous zeotype materials for use as ultracapacitors in energy storage applications.